Benjamin Peter Horton

200 million people worldwide live along coastlines less than 5 metres above sea level. By the end of the 21st century this figure is estimated to increase to 400 to 500 million. These low-lying coastal regions vulnerable to changes in sea level brought about by climate change, storms or earthquakes. My research uncovers fundamental knowledge about how sea level has changed in the past and how it may change in the future. My findings therefore impact upon important ethical, social, economic and political problems specifically facing such coastal regions. The Intergovernmental Panel on Climate Change (IPCC) re-emphasized the importance of sea level as a barometer of climate and drew attention to the potentially devastating consequences of future climate change. The IPCC highlighted the uncertainty with which the driving mechanisms of recent sea-level change are understood and the disconnect between long-term geological and recent observational trends (e.g., Dutton et al., 2015). My research directly addresses the rates and geographic variability of sea-level change, which was highlighted at the top of the list of the eight priority science questions in the “Sea Change: 2015-2025 Decadal Survey of Ocean Sciences” report (NRC, 2015). The study of sea-level change was subsequently recommended as Strategic Research Priority I in “A Strategic Vision for NSF Investments in Antarctic and Southern Ocean Research” (NAS, 2015). An incomplete understanding of the earthquake and tsunami hazards associated with the Sunda and Japan subduction zones contributed to the devastating societal impacts of the 2004 Indian Ocean and 2011 Tohoku events. Instrumental records of previous earthquakes and tsunamis proved too short to estimate the potential magnitude and recurrence interval of such great events that recur centuries to millennia apart. My earthquake and tsunami records on centennial and millennial temporal scales are necessary to understanding long-term subduction zone behavior and the occurrences of large, but infrequent events. Tropical Cyclones and their associated storm surges are among the most destructive natural disasters to impact coastal regions. The severity and frequency of coastal floods is increasing (and will worsen in most locations over the 21st century. But the short timescale and narrow range of 20th century forcing captured by the instrumental record may not address important mechanisms underlying the dramatic changes expected in the late 21st century. My reconstructions of paleo storms reveal spatial and temporal variability of tropical cyclone activity and provided insight into their relationship with global climatic changes.